The present invention relates to a sample introducing device for introducing a sample solution into an inductively coupled plasma emission spectroscopic analyzer (hereinafter referred to as ICP-AES) or an inductively coupled plasma mass spectrometric analyzer (hereinafter referred to as ICP-MS), which performs identification and qualification of trace impurity in a sample solution.
The prior art is explained by referring to FIG. 2.
In FIG. 2, reference numeral 1 is a washing liquid, reference numeral 2 is a sample solution, reference numerals 3a and 3b are liquid feed pumps, reference numerals 4a, 4b and 4c are tubes, reference numeral 5 is a hexagonal valve, reference numeral 6 is a rotor, reference numerals 7a, 7b, 7c, 7d, 7e and 7f are joints, reference numeral 8 is a sample loop, and reference numeral 9 is a nebulizer.
The washing liquid 1 reaches the joint 7a of the hexagonal valve 5 through the liquid feed pump 3a and the tube 4a. Further, the sample solution 2 reaches the joint 7b of the hexagonal valve 5 through the liquid feed pump 3b and the tube 4b. The liquid feed pumps 3a and 3b used are a "stroke" type pump such as a peristaltic pump. When the washing liquid 1 is introduced into the nebulizer 9, the washing liquid 1 reaches the joint 7f through the hexagonal valve 5 and holes opened on the rotor 6 from the joint 7a and then reaches the nebulizer 9 through the tube 4c as shown in FIG. 2. At this time, the sample solution 2 flows in the order of the joint 7b, the sample loop 8, the joint 7e and the joint 7d from the joint 7c, and the sample loop 8 is filled with the sample solution 2. Analysis of the sample solution 2 is conducted by introducing the sample solution filled in the sample loop 8 into the inductively coupled plasma analyzer. At this time, the rotor 6 rotates, and the joints 7a and 7b, the joint 7c and 7d, and the joints 7e and 7f are connected in the hexagonal valve 5 as shown in FIG. 3.
The sample solution in the sample loop 8 is press-flown by the liquid feed pump 3a to reach the nebulizer 9.
The inductively coupled plasma analyzer is comprised of the nebulizer 9, a spray chamber 10, a plasma torch 11, a work coil 12, a high-frequency electric source, and an analyzing pipe 14. The nebulizer 9 acts to atomize the sample solution 2 or the washing liquid 1 introduced into a mist form The spray chamber 10 acts to sieve a particle diameter of the mist atomized. However, in recent inductively coupled plasma analyzers, there is an analyzer that omits the spray chamber 10 and directly leads the mist generated by the nebulizer 9 to the plasma torch The work coil 12 is wound around the tip of the plasma torch 11, and a high-frequency electric power of 27 MHz or 40 MHz is applied to the work coil 12 from the high-frequency electric source 13. By this high-frequency electric power, the mist of the sample solution 2 introduced into the plasma torch 11 forms a plasma 15 together with a gas (not shown) such as argon simultaneously introduced. The analyzing pipe 14 is a pipe to analyze an ion or a light of an impurity element contained in the sample solution in the plasma 15. The analyzing pipe 14 conducts identification of an impurity from a wavelength of light and conducts quantification from an intensity in ICP-AES, and conducts identification of impurity from a mass of an ion and conducts quantification from an intensity (ion counting rate or counting number).
However, the prior art involves the following problems. The first is a memory effect. In the conventional sample introducing device, the sample solution passes through plural joints or boundary of the rotor in the hexagonal valve, and a liquid is liable to retained at the boundary of the joints or the rotor. For this reason, when plural sample solutions are analyzed, the sample solution retained and left has influence on the analytical results of the subsequent samples. This problem is particularly important in an apparatus that conducts a super-high sensitivity analysis in ppt level, such as ICP-MS. The second is a problem on the change of an amount of the sample solution introduced into the inductively coupled plasma analyzer.
In the conventional sample introducing device the change in the amount of the sample solution introduced is required to replace the sample loop. This work is not only complicated, but also has the risk that the sample introducing device is contaminated with the external environment or the operator himself.
The present invention solves the above-mentioned problems and provides a sample introducing device which does not suffer from the disadvantages of the memory effect and contamination, and which is capable of easily changing the amount of the sample solution introduced into the inductively coupled plasma analyzer. The present invention also provides a sample introducing device for an inductively coupled plasma analyzer, which is capable of securely detecting the signal of trace impurity in the sample solution.